The present invention relates generally to an electrical connector and, more particularly, to a socket for connecting a pin grid-array (xe2x80x9cPGAxe2x80x9d) package to a circuit member and terminals within the socket.
A typical PGA package includes a silicon chip, a package including conductive and non-conductive components and a plurality of lead pins in a grid array depending downward from a bottom surface of the package. Conventionally, sockets for PGA packages include a plate-like base housing having a plurality of terminals arranged in the same grid pattern as the lead pins of the PGA package and a plate-like cover member having a plurality of through holes in the same grid pattern as the lead pins of the pin grid-array package, thus permitting the lead pins to be inserted in the through holes. The plate-like cover member is slidably positioned on the upper surface of the base housing. Some examples of such sockets are shown in Japanese Patent Application Laid-Open No. 7-142134 and Japanese Registered Utility Model No. 2-536440.
The base housing and cover are slidably interconnected so that the cover is driven in a plane parallel to the underlying base housing between a first position in which the lead pins of the PGA package can pass through the through holes of the cover to reach the terminals mounted in the underlying base housing without requiring any insertion force to be applied to the lead pins and a second position in which the lead pins of the PGA package contact the terminals.
A variety of terminal structures have been proposed as appropriate for use in such sockets. Some such terminals are configured such that their contact portions engage the lead pins of a PGA package upon movement of the cover of the socket, as shown in Japanese Patent Application Laid-Open No. 7-142134 and Japanese Registered Utility Model No. 2-536440 referred to above. Conversely, some terminals are configured such that the lead pins of a PGA package are brought to the contact portions of terminals in the base housing as shown in Japanese Patent Application Laid-Open Nos. 9-185981 and 9-204969.
Essentially all of the prior art terminals have contact portions located in the terminal-receiving cavities of the base housing of the socket, and most have straight pin-like solder tails extending from the bottom of the base housing of the socket. These pin-like solder tails are inserted into through holes of a printed circuit board on which the socket is mounted, and are soldered to the printed circuit board.
The base housing typically has some type of drive mechanism formed thereon for slidably moving the cover over the underlying base housing. In some sockets, a cam is rotatably attached to one lateral side or end of the base housing, and the cam is adapted to be rotated with an associated handle, thereby permitting the cam axle to push or pull the cover over the underlying base housing. The handle may be rotated from a horizontal position in which it is parallel to the base housing to a vertical position in which it is perpendicular to the base housing.
The demand for ever smaller electronic devices has driven the demand for smaller components that make up the electronic devices. However, customers also desire increasing performance from these smaller devices. Thus, component designers must continue to shrink their designs while still improving their performance and ease of use.
One object of the present invention is to provide a socket for a pin grid-array package, the parts of which socket are so designed that the socket can be produced at an increased efficiency.
To attain this object, a socket assembly for a pin grid-array package includes a plate-like base housing having a plurality of terminals arranged in the form of a grid and mounted therein for making electric connection to respective ones of lead pins of a pin grid-array package. A plate-like slide cover has a corresponding plurality of through holes therein for accommodating the lead pins and the plate-like cover is positioned on the upper surface of the base housing. A slide drive is provided to move the slide cover between a first position at which the lead pins can be inserted in the terminals of the base housing with zero insertion force after passing through the through holes of the cover and a second position at which the lead pins engage the terminals of the base housing. The terminal cavities in the base housing each include an upper opening in the upper surface of the base housing, and a lower hole in the bottom of the base housing. Each of the terminals is press-fit into a selected terminal cavity from above, allowing its soldering tail to pass through the lower hole so that the solder tail extends from the bottom of the base housing.
Each terminal may comprise a rectangular base, two opposing contact pieces integrally connected to the opposite longitudinal sides of the rectangular base and rising generally upright therefrom, and a xe2x80x9cUxe2x80x9d-shaped engagement piece integrally connected to one lateral side of the rectangular base via a first joint arm which extends upward. The opposing contact pieces and the xe2x80x9cUxe2x80x9d-shaped engagement piece may be equal in height, and equal to the depth of the terminal cavity, thus permitting the xe2x80x9cUxe2x80x9d-shaped engagement piece to be pushed against the surrounding wall of the base housing.
The terminal may further comprise a tail integrally connected to the rectangular base opposite the first joint arm via a second joint arm, which extends downward below the rectangular base. The lower hole is large enough to allow the tail to pass therethrough when the terminal is press-fit into the terminal cavity from above.
The terminals may also include two resilient detent projections or arms integrally connected to the other lateral side of the rectangular base, inclining upward from the opposite sides of the second joint arm, in which case each of the terminal cavities will have step-like indentations made in their inner walls to catch the opposite detent projections when a terminal is press-fit into the terminal cavity.
Another object of the present invention is to provide a terminal structure as described above that is appropriate for use in such a socket.